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45-416: NGF may refer to: Nerve growth factor Naval gunfire Northern Group of Forces National Golf Foundation Non-Growing Follicles, see Folliculogenesis North German Federation New Generation Fighter, see Future Combat Air System Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

90-538: A chili pepper (due to its main ingredient, capsaicin), the cold sensation experienced after ingesting a chemical such as menthol or icillin, as well as the common sensation of pain are all a result of neurons with these receptors. Problems with mechanoreceptors lead to disorders such as: Internal receptors that respond to changes inside the body are known as interoceptors . The aortic bodies and carotid bodies contain clusters of glomus cells – peripheral chemoreceptors that detect changes in chemical properties in

135-452: A licensed medicine in China since 2003. There is evidence of improved patient outcomes for several diseases of the nervous system, including acute intracerebral hemorrhage, global developmental delay, optic atrophy, epilepsy and cerebral palsy. This is significant as there are few medicines which can treat injuries and diseases of the nervous system. Research and clinical use outside of China

180-443: Is a neurotrophic factor and neuropeptide primarily involved in the regulation of growth, maintenance, proliferation, and survival of certain target neurons . It is perhaps the prototypical growth factor , in that it was one of the first to be described. Since it was first isolated by Nobel Laureates Rita Levi-Montalcini and Stanley Cohen in 1956, numerous biological processes involving NGF have been identified, two of them being

225-424: Is a sensory system disorder in which amputees perceive that their amputated limb still exists and they may still be experiencing pain in it. The mirror box developed by V.S. Ramachandran, has enabled patients with phantom limb syndrome to relieve the perception of paralyzed or painful phantom limbs. It is a simple device which uses a mirror in a box to create an illusion in which the sensory system perceives that it

270-457: Is a warmth-sensitive receptor. Mechanoreceptors are sensory receptors which respond to mechanical forces, such as pressure or distortion . Specialized sensory receptor cells called mechanoreceptors often encapsulate afferent fibers to help tune the afferent fibers to the different types of somatic stimulation. Mechanoreceptors also help lower thresholds for action potential generation in afferent fibers and thus make them more likely to fire in

315-440: Is constitutively active, neurons survive even without NGF. A second pathway contributing to cell survival occurs through activation of the mitogen-activated protein kinase ( MAPK ) kinase. In this pathway, recruitment of a guanine nucleotide exchange factor by the adaptor and docking proteins leads to activation of a membrane-associated G-protein known as Ras . The guanine nucleotide exchange factor mediates Ras activation through

360-451: Is evidence that pancreatic beta cells express both the TrkA and p75NTR receptors of NGF. It has been shown that the withdrawal of NGF induces apoptosis in pancreatic beta cells, signifying that NGF may play a critical role in the maintenance and survival of pancreatic beta cells. NGF plays a critical role in the regulation of both innate and acquired immunity. In the process of inflammation , NGF

405-501: Is limited despite a large body of evidence supporting its use. Recombinant human nerve growth factor (rhNGF; named cenegermin ) has been formulated as an eye drop (0.002%).  In 2018 it was approved by the FDA for the treatment of neurotrophic keratitis , a disease in which corneal nerves are damaged or nonfunctional.  Without normal corneal sensation, the corneal epithelium does not heal after injury or infection, leading to melting of

450-669: Is released in high concentrations by mast cells , and induces axonal outgrowth in nearby nociceptive neurons. This leads to increased pain perception in areas under inflammation. In acquired immunity, NGF is produced by the Thymus as well as CD4+ T cell clones , inducing a cascade of maturation of T cells under infection. NGF is abundant in seminal plasma. Recent studies have found that it induces ovulation in some mammals e.g. "induced" ovulators, such as llamas. Surprisingly, research showed that these induced animals will also ovulate when semen from on-schedule or "spontaneous" ovulators, such as cattle

495-408: Is used. Its significance in humans is unknown. It was previously dubbed ovulation-inducing factor (OIF) in semen before it was identified as beta-NGF in 2012. NGF binds with at least two classes of receptors: the tropomyosin receptor kinase A (TrkA) and low-affinity NGF receptor (LNGFR/p75NTR). Both are associated with neurodegenerative disorders . When NGF binds to the TrkA receptor, it drives

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540-589: The primary structure of NGF. This eventually led to the discovery of the NGF gene. NGF is abundant in seminal plasma. Recent studies have found that it induces ovulation in some mammals. Nerve Growth Factors (NGF) were initially discovered due to their actions during development, but NGF are now known to be involved in the function throughout the life of the animal. Nerve growth factor has been shown to interact with Tropomyosin receptor kinase A . NGF, specifically mouse (murine) nerve growth factor, has been available as

585-626: The 1950s while faculty members at Washington University in St. Louis . The critical discover was done by Levi-Montalcini and Hertha Meyer at the Carlos Chagas Filho Biophysics Institute of the Federal University of Rio de Janeiro in 1952. Their publication in 1954 became the definitive proof for the existence of the protein. Levi-Montalcini later remarked: The tumor had given a first hint of its existence in St. Louis but it

630-626: The GDP-GTP exchange process. The active Ras protein phosphorylates several proteins, along with the serine/threonine kinase, Raf . Raf in turn activates the MAPK cascade to facilitate ribosomal s6 kinase (RSK) activation and transcriptional regulation. Both Akt and RSK, components of the PI3K-Akt and MAPK pathways respectively, act to phosphorylate the cyclic AMP response element binding protein ( CREB ) transcription factor. Phosphorylated CREB translocates into

675-555: The Trk receptor complex-recruitment of a second adaptor protein called growth factor-receptor bound protein-2 ( Grb2 ) along with a docking protein called Grb2-associated Binder-1 ( GAB1 ). Subsequently, phosphatidylinositol-3 kinase ( PI3K ) is activated, resulting in Akt kinase activation. Study results have shown that blocking PI3K or Akt activity results in death of sympathetic neurons in culture, regardless of NGF presence. However, if either kinase

720-471: The activation of PI 3-kinase , ras , and PLC signaling pathways. Alternatively, the p75NTR receptor can form a heterodimer with TrkA, which has higher affinity and specificity for NGF. Studies suggest that NGF circulates throughout the entire body via the blood plasma, and is important for the overall maintenance of homeostasis . Binding interaction between NGF and the TrkA receptor facilitates receptor dimerization and tyrosine residue phosphorylation of

765-466: The air. The molecules in the air are detected by enlarged cilia and microvilli . These sensory neurons produce action potentials. Their axons form the olfactory nerve , and they synapse directly onto neurons in the cerebral cortex ( olfactory bulb ). They do not use the same route as other sensory systems, bypassing the brain stem and the thalamus. The neurons in the olfactory bulb that receive direct sensory nerve input, have connections to other parts of

810-428: The auditory system leads to disorders such as: Thermoreceptors are sensory receptors, which respond to varying temperatures . While the mechanisms through which these receptors operate is unclear, recent discoveries have shown that mammals have at least two distinct types of thermoreceptors. The bulboid corpuscle , is a cutaneous receptor a cold-sensitive receptor, that detects cold temperatures. The other type

855-536: The blood such as oxygen concentration. These receptors are polymodal responding to a number of different stimuli. Nociceptors respond to potentially damaging stimuli by sending signals to the spinal cord and brain. This process, called nociception , usually causes the perception of pain . They are found in internal organs as well as on the surface of the body to "detect and protect". Nociceptors detect different kinds of noxious stimuli indicating potential for damage, then initiate neural responses to withdraw from

900-578: The body are called exteroreceptors . Exteroreceptors include chemoreceptors such as olfactory receptors ( smell ) and taste receptors , photoreceptors ( vision ), thermoreceptors ( temperature ), nociceptors ( pain ), hair cells ( hearing and balance ), and a number of other different mechanoreceptors for touch and proprioception (stretch, distortion and stress). The sensory neurons involved in smell are called olfactory sensory neurons . These neurons contain receptors , called olfactory receptors , that are activated by odor molecules in

945-520: The body, for example those that detect light and sound, or from interoreceptors inside the body, for example those that are responsive to blood pressure or the sense of body position . Sensory neurons in vertebrates are predominantly pseudounipolar or bipolar , and different types of sensory neurons have different sensory receptors that respond to different kinds of stimuli . There are at least six external and two internal sensory receptors: External receptors that respond to stimuli from outside

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990-423: The brain of Taub's Silver Spring monkeys , there has been a large amount of research into sensory system plasticity . Huge strides have been made in treating disorders of the sensory system. Techniques such as constraint-induced movement therapy developed by Taub have helped patients with paralyzed limbs regain use of their limbs by forcing the sensory system to grow new neural pathways . Phantom limb syndrome

1035-448: The brain. The brain then processes these signals and interprets them as specific taste sensations, allowing you to perceive and enjoy the flavors of the foods you consume. When taste receptor cells are stimulated by the binding of these chemical compounds (tastants), it can lead to changes in the flow of ions, such as sodium (Na+), calcium (Ca2+), and potassium (K+), across the cell membrane. In response to tastant binding, ion channels on

1080-462: The corneal stroma and recurrent infections.  Clinical trials of cenegermin indicate that the drug can increase the rate of healing of the epithelium. Sensory neurons The sensory information travels on the afferent nerve fibers in a sensory nerve , to the brain via the spinal cord . Spinal nerves transmit external sensations via sensory nerves to the brain through the spinal cord. The stimulus can come from exteroreceptors outside

1125-453: The cytoplasmic tail by adjacent Trk receptors. Trk receptor phosphorylation sites operate as Shc adaptor protein docking sites, which undergo phosphorylation by the TrkA receptor Once the cytoplasmic adaptor protein (Shc) is phosphorylated by the receptor cytoplasmic tail, cell survival is initiated through several intracellular pathways. One major pathway leads to the activation of the serine/threonine kinase, Akt . This pathway begins with

1170-698: The death domain of the p75NTR cytoplasmic tail. Survival occurs when recruited cytoplasmic adaptor proteins facilitate signal transduction through tumor necrosis factor receptor members such as TRAF6 , which results in the release of nuclear factor κB ( NF-κB ) transcription activator. NF-κB regulates nuclear gene transcription to promote cell survival. Alternatively, programmed cell death occurs when TRAF6 and neurotrophin receptor interacting factor (NRIF) are both recruited to activate c-Jun N-terminal kinase (JNK); which phosphorylates c-Jun. The activated transcription factor c-Jun regulates nuclear transcription via AP-1 to increase pro-apoptotic gene transcription. There

1215-561: The homodimerization of the receptor, which in turn causes the autophosphorylation of the tyrosine kinase segment. The tropomyosin receptor kinase A receptor has five extracellular domains, and the fifth domain is sufficient in binding NGF. Once bound, the complex undergoes endocytosis and activates the NGF transcriptional program, following two major pathways, the Ras/MAPK pathway and the PI3K/Akt pathway . The binding of NGF to TrkA also leads to

1260-438: The intensity of light, allowing for vision in dim lighting. The concentrations and ratio of rods to cones is strongly correlated with whether an animal is diurnal or nocturnal . In humans, rods outnumber cones by approximately 20:1, while in nocturnal animals, such as the tawny owl , the ratio is closer to 1000:1. Retinal ganglion cells are involved in the sympathetic response . Of the ~1.3 million ganglion cells present in

1305-417: The interactions with other types of neurons in the retina. The five basic classes of neurons within the retina are photoreceptor cells , bipolar cells , ganglion cells , horizontal cells , and amacrine cells . The basic circuitry of the retina incorporates a three-neuron chain consisting of the photoreceptor (either a rod or cone ), bipolar cell, and the ganglion cell. The first action potential occurs in

1350-435: The market that are used to manipulate or treat sensory system disorders. For instance, gabapentin is a drug that is used to treat neuropathic pain by interacting with one of the voltage-dependent calcium channels present on non-receptive neurons. Some drugs may be used to combat other health problems, but can have unintended side effects on the sensory system. Dysfunction in the hair cell mechanotransduction complex, along with

1395-559: The movement, the hair cell can either hyperpolarize or depolarize. When the movement is towards the tallest stereocilia , the Na cation channels open allowing Na to flow into cell and the resulting depolarization causes the Ca channels to open, thus releasing its neurotransmitter into the afferent auditory nerve. There are two types of hair cells: inner and outer. The inner hair cells are the sensory receptors . Problems with sensory neurons associated with

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1440-428: The nucleus and mediates increased expression of anti-apoptotic proteins, thus promoting NGF-mediated cell survival. However, in the absence of NGF, the expression of pro-apoptotic proteins is increased when the activation of cell death-promoting transcription factors such as c-Jun are not suppressed by the aforementioned NGF-mediated cell survival pathways. Rita Levi-Montalcini and Stanley Cohen discovered NGF in

1485-485: The olfactory system and many parts of the limbic system . 9. Taste sensation is facilitated by specialized sensory neurons located in the taste buds of the tongue and other parts of the mouth and throat. These sensory neurons are responsible for detecting different taste qualities, such as sweet, sour, salty, bitter, and savory. When you eat or drink something, chemicals in the food or liquid interact with receptors on these sensory neurons, triggering signals that are sent to

1530-496: The potential loss of specialized ribbon synapses, can lead to hair cell death, often caused by ototoxic drugs like aminoglycoside antibiotics poisoning the cochlea. Through the use of these toxins, the K+ pumping hair cells cease their function. Thus, the energy generated by the endocochlear potential which drives the auditory signal transduction process is lost, leading to hearing loss. Ever since scientists observed cortical remapping in

1575-453: The presence of sensory stimulation. Some types of mechanoreceptors fire action potentials when their membranes are physically stretched. Proprioceptors are another type of mechanoreceptors which literally means "receptors for self". These receptors provide spatial information about limbs and other body parts. Nociceptors are responsible for processing pain and temperature changes. The burning pain and irritation experienced after eating

1620-403: The protein into functional NGF. The term nerve growth factor usually refers to the 2.5S, 26-kDa beta subunit of the protein, the only component of the 7S NGF complex that is biologically active (i.e. acting as a signaling molecule). As its name suggests, NGF is involved primarily in the growth, as well as the maintenance, proliferation, and survival of nerve cells (neurons) and is critical for

1665-405: The retina, 1-2% are believed to be photosensitive. Issues and decay of sensory neurons associated with vision lead to disorders such as: The auditory system is responsible for converting pressure waves generated by vibrating air molecules or sound into signals that can be interpreted by the brain. This mechanoelectrical transduction is mediated with hair cells within the ear. Depending on

1710-451: The retinal ganglion cell. This pathway is the most direct way for transmitting visual information to the brain. There are three primary types of photoreceptors: Cones are photoreceptors that respond significantly to color . In humans the three different types of cones correspond with a primary response to short wavelength (blue), medium wavelength (green), and long wavelength (yellow/red). Rods are photoreceptors that are very sensitive to

1755-455: The sensations in terms of which cells are active. A sensory receptor's adequate stimulus is the stimulus modality for which it possesses the adequate sensory transduction apparatus. Adequate stimulus can be used to classify sensory receptors: Sensory receptors can be classified by location: Somatic sensory receptors near the surface of the skin can usually be divided into two groups based on morphology: There are many drugs currently on

1800-414: The stimulus. Information coming from the sensory neurons in the head enters the central nervous system (CNS) through cranial nerves . Information from the sensory neurons below the head enters the spinal cord and passes towards the brain through the 31 spinal nerves . The sensory information traveling through the spinal cord follows well-defined pathways. The nervous system codes the differences among

1845-875: The survival and maintenance of sympathetic and sensory neurons as they undergo apoptosis in its absence. However, several recent studies suggest that NGF is also involved in pathways besides those regulating the life cycle of neurons. NGF can drive the expression of genes such as bcl-2 by binding to the Tropomyosin receptor kinase A , which stimulates the proliferation and survival of the target neuron. High affinity binding between proNGF, sortilin, and p75NTR can result in either survival or programmed cell death . Study results indicate that superior cervical ganglia neurons that express both p75NTR and TrkA die when treated with proNGF, while NGF treatment of these same neurons results in survival and axonal growth. Survival and PCD mechanisms are mediated through adaptor protein binding to

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1890-456: The survival of pancreatic beta cells and the regulation of the immune system . NGF is initially in a 7S, 130- kDa complex of 3 proteins – Alpha-NGF, Beta-NGF, and Gamma-NGF (2:1:2 ratio) when expressed. This form of NGF is also referred to as proNGF (NGF precursor). The gamma subunit of this complex acts as a serine protease, and cleaves the N-terminal of the beta subunit, thereby activating

1935-484: The taste receptor cell membrane can open or close. This can lead to depolarization of the cell membrane, creating an electrical signal. Similar to olfactory receptors , taste receptors (gustatory receptors) in taste buds interact with chemicals in food to produce an action potential . Photoreceptor cells are capable of phototransduction , a process which converts light ( electromagnetic radiation ) into electrical signals. These signals are refined and controlled by

1980-708: The title NGF . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=NGF&oldid=1024355970 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Nerve growth factor 4ZBN , 1SG1 , 1WWW , 2IFG , 4EDW , 4EDX 4803 18049 ENSG00000134259 ENSMUSG00000027859 P01138 P01139 NM_002506 NM_001112698 NM_013609 NP_002497 NP_001106168 NP_038637 Nerve growth factor ( NGF )

2025-619: Was in Rio de Janeiro that it revealed itself, and it did so in a theatrical and grand way, as if spurred by the bright atmosphere of that explosive and exhuberant manifestation of life that is the Carnival in Rio. However, its discovery, along with the discovery of other neurotrophins, was not widely recognized until 1986, when it won the Nobel Prize in Physiology or Medicine. Studies in 1971 determined

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